1. Field of the Invention
The present invention relates to a navigation unit, and, more particularly, to a navigation unit having a selectively positionable gyro sensor mounted therein.
2. Related Art
Navigation systems for use in vehicles are conventionally constructed to include: a display device having a display for displaying data; a control unit allowing a driver to input data; a receiver for using a variety of media; a CD-ROM driver for using a CD-ROM; and a navigation unit for supervising the entirety of the navigation system. The navigation unit includes a variety of electronic parts such as a CPU, a memory and an interface, a card holder for holding a feature expansion PC card, and a gyro sensor for detecting the direction of travel of the vehicle. The navigation unit is usually mounted in a trunk of the vehicle, and is connected with the receiver and the CD-ROM driver, also mounted in the trunk, and with the display device mounted in the passenger compartment near the driver's seat.
Conventional navigation units, however, have such a large size and occupy so much space that they are difficult to mount on a vehicle. In order to improve the mountability, therefore, attempts have been made to provide a navigation unit which can be installed either horizontally or vertically on the vehicle. However, since the gyro sensor must have its rotation detecting axis vertical at all times, it cannot be used in a navigation unit which can be installed either horizontally or vertically. Thus, in these navigation units the gyro unit having the gyro sensor is made separate from the remainder of the navigation unit so that the gyro unit is installed directly on the vehicle. In this latter case, however, the total space occupied by the navigation unit and the gyro unit is enlarged. In addition, the work for installing the gyro unit directly on the vehicle is troublesome, and communication circuits or the like are required between the navigation unit and the gyro unit, thus raising cost.
Navigation units have also been constructed for horizontal installation with two gyro sensors, having different mounting directions, mounted therein. In this construction, when one gyro sensor is mounted vertically in the navigation unit, the other gyro sensor can also be used. However, the two gyro sensors must be mounted in advance in the navigation unit, thus increasing cost and occupied area.